The present invention relates to the field of mechanical systems for controlling displacement. For example a device of the invention can be used to control rapidly accelerated displacement that could give rise to an operational problem or to a safety problem.
More particularly, but in non-limiting manner, the device can be used in high-impulse projectile launchers that need to have two different dynamic behaviors in damping.
The invention is particularly, but not exclusively, applicable to friction dampers of the type described in document FR 2 697 881. A damper device of that type comprises a fixed portion, a moving portion, and friction means interposed between the fixed portion and the moving portion.
The object of the invention is to improve the dynamic behavior in damping. This object is achieved by a mechanical device that has two modes of relative displacement between one assembly and another, with the transition between the two modes being controlled and determined by the time profile of the relative displacement.
More precisely, the object of the invention is to propose a mechanical device making it possible to manage response to external stress as a function of the amplitude of the impulse generated:
if the external stress generates low impulse (below a pre-established threshold), then the system should remain in a first relative displacement mode, i.e. it should move freely;
if the external stress generates a high impulse (greater than a pre-established threshold), then the system must change over to a second relative displacement mode, i.e. with damping or blocking.
In the context of the present invention, this object is achieved by a mechanical device for controlling changeover between two modes of relative displacement between two objects comprising:
two assemblies capable of moving in guided relative translation, one assembly being said to be fixed, and the other being said to be moving,
the device further comprising:
resilient control means interposed between the two assemblies with a controlled clearance to define the mode of relative displacement; and
an inertial mass associated with one of the assemblies and adapted to act selectively on the control means as a function of the time profile of moving assembly displacement in order to modify the clearance and the mode of relative displacement.